US 3167850 A
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Feb. 2, 1965 F. w. BRODERICK TRANSFER ROLL Filed Dec. 21, 1962 United States Patent 3,167,850 TRANSFER ROLL Frank W. Broderick, P.0. Box 2, Stirling, NJ. Filed'Dec. 21, 1962, Ser. No. 246,627 3 Claims. (Cl. 29-121) This invention relates to an engraved metal roll having patterned cavities therein adapted to uniformly transfer metered amounts of solution to a non-Woven fabric in tangential contact therewith.
In the manufacture of non-woven fabric from long fila- The engraved design disposed on the application roll is A of such depth and configuration asto transfer the solution to the non-woven fabric, in extremely closely held tolerances, said solution being then spread by capillary action in given areas to yield a moistened binding channel having a uniform amount of solution per square inch.
The production of non-woven fabric is big business, as the material is used for disposable diapers, sanitary napkins, suit paddings, wiper cloths, napkins, etc.
The present method of making engraved transfer rolls is by meansof a conventional mill and die wherein a small female roll is first prepared and from this a coacting small male roll is made. This male roll of a few inches in length is then repeatedly linearly transferred to the surface of a large, sometimes six to ten feet long, production roll. Clearly, this procedure is very expensive since it requires highly skilled labor and is very cumbersome and time consuming.
Attempts have been made to produce a suitable acid etched engraved transfer roll using conventional acid resist coatings but the resulting embossed cavities of the pattern were provided with undesirable saw tooth or ragged edges which engaged or picked up the tiny fila ments of the fabric, a highly undesirable result.
Accordingly, it is impossible to produce satisfactory acid etched embossed steel transfer rolls of the type desired above before this invention was made.
In the conventional method of etching steel rolls, as described for example in Broderick US. 2,887,042, a relatively soft steel roll is photo-engraved and then acid etched to the desired depth and finally heat hardened to withstand usage.
This invention reverses the prior art and in so doing produces a new process with unobvious desirable results.
According to this invention the soft steel roll is suitably heat hardened before it is photo-engraved. This heat hardening, it was found, refined the steel grain structure so that the roll could be now acid etched to produce smooth cavities having straight and uniform edges in lieu of the prior art saw tooth edges and irregular depths.
It is an object of this invention to produce acid etched engraved metal transfer rolls for the transfer of uniform amounts of solution to non-woven fabric, the cavities thereof having smooth, straight or snag proof edges.
It is another object to provide an inexpensive snag proof transfer roll.
It is a further object to provide an engraved pattern having great accuracy and uniform depth of cavities.
These and other objectives of this invention will become apparent upon reading the following descriptive disclosure taken in conjunction with the accompanying drawing in which:
FIG. 1 is a diagrammatic perspective view of a schematic engraved roll disposed in part in a fountain containing the binder or adhesive solution and showing the use of a doctor blade to scrape off excess solution from the surface,
FIG. 2 is a cross-section view of a heat hardened acid etched metal roll showing the smooth, accurate edges and smooth, rounded internal contour of a single linear cavity as produced by this invention,
FIG. 3 is a section view of the roll of FIG. 2 after being chrome plated, showing the manner of chrome plating building up on the round edges. of the cavities, and
FIG.'4 is the cross-section view of the roll of FIG. 3 after the built-up or hump-like rounded edges have been polished off to produce a chrome plated transfer roll of uniform radius.
In the use of this invention there is employed a binder or adhesive solution used to bind or adhere the non- Woven fibers together. This solution is disposed in a trough or fountain and the embossed transfer roll is partly placed therein. A doctor blade engages the smooth surface of the transfer roll and removes the excess solution thereon. The amount of solution transferred to the web is critical since too little solution will not effect a binding together of the fibrous filaments and too much cured removeably thereto. An embossed transfer roll 12,
for example of herringbone pattern, is disposed partly in the fountain 10. A continuously moving web 13 of nonwoven fibers is passed tangentially over the top of the embossed transfer roll 12 and engages on its opposed side a backup roll 14. The, binder solution strikes through the non-woven fabric to the opposite side thereof binding the long fibers in the manner similar to that of a stitched line. In short, the binder solution from the rotating cavities is transferred to the moving web and in effect stitches the long fibers laterally to form a semi-quilted soft nonwoven fabric.
To effect this critical uniformity of binder, the engraved rolls must have a precisely predetermined pat-tern and this pattern must accurately transfer a critical amount of solution per lateral area or circumferential surface.
According to this invention, a polished suitable high carbon steel or steel alloy roll is heat hardened, preferably by flame hardening to a desired fine grain structure. Preferably this desired fine grain structure is produced throughout the steel roll. However, a fine grain structure in the surface of suitable depth on the radius is operable.
This fine grain structure is homogeneous throughout the pattern area and depth and is essential and critical to the success of this invention.
By way of an illustrative embodiment of this invention a smooth surfaced forged chrome-molybdenum steel roll, AISI 4150, having the following composition:
Carbon range 0.45-0.55% by weight Manganese range 0.60-0.90% by weight Phosphorous (maximum) 0.040% by weight Sulfur (maximum) 0.050% by weight Chromium range, about 0.80 to about 1.10% by weight Molybdenum range, about 0.15 to about 0.25% by weight was flame hardened to a critical transformation temperature of 1575 F. to produce the desired homogeneous fine grain structure as shown by microscopic examination and by a Rockwell hardness tester C scale reading of 53. At this temperature the finest grain structure was obtained which structure gave the smoothest cavities on acid etchmg.
Other chrome-molybdenum alloy steels in the range of the AISI 4150 composition are operable. In general, the
alloy steel is heatedto within ten degrees Fahrenheit of their final transformation point in order toobtain the desired fine grain structure. Such heat treated steels exhibit a Rockwell C scale hardness reading generally from 45-60 and:are operable in-this invention. However, in the case of the chrome-molybdenum steels a heat treated alloy treated as above statedpreferably has a Rockwell C scale reading of 50m 55 c In all cases after the alloy is heated to its finaltransformation temperature it is quenched immediately at this temperature to obtain and retain the desired fine grain structure plus the desired hardness.
Next this smooth surfaced roll Wasphoto-engraved with a desired pattern by means of the conventional lay down Moreover, the disastrous saw tooth The rollers arethen chrome plated to a depthof .0006 1 to .002 or more inch to produce a chrome plated surface Plating of this thickness and-quality tends to build up i at the edges of the aembossedcavities producing a hump 16 thereon. This hump of chrome is thicker than on the surface and it may be polished off to produce a non hurnp slightly'roundedredge 17 of uniform chrome plate depth (FIG. 4). v
The resultant chrome plated roll is therefore one of uniform depth of cavities, said cavities having round snag- This invention has been described by means of several embodiments .thereoflbut .is not limited 10 these illll I ations since itis of a generic scope. V I a I claim:
1. A- snag-proof transfer roll of chrome-molybdenum alloy 'steel engraved for uniform transfer of fluid to a moving monofilament web, said roll. having ,a Rockwell C scale hardness of from .to and having a fine I 1.10 percent by weight'and the mol-ybdenumrangeabout.
0.15 to about 0.25,percent -by weight.
' 2.1The transfer roll of claim *1 wherein thecritical transformation temperature is 1575 and the Rockwell "C scale reading is 53. V
3. The transfer roll of claimd comprising a smooth surface uniformly deep chromeplating of a depth of .0006 to .002 inch..
References Cited by the 'Examiner UNITED STATES iPATENTS 2,114,072 '4/ 3 8 Cleveland. 2,725,640 '12/52 Voightman; 2,816,025 12/ 5-7 Dahlberg. V
- 3,048,512 8/ 62 Nelson.
.WALTERA. SCHEELPrimary Examiner.
I. D. .BEIN, Examiner.-
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